Change move folder form to not have default radio btn and to show hint

Updated the move folder form to add a hint for the radio button for the
current folder saying 'current folder'. This hint does not get shown if
you are viewing all folders (so you are not inside a folder).

Also stopped a default radio button from being selected on the form.

app/main/forms.py

@@ -1287,6 +1287,7 @@ class TemplateAndFoldersSelectionForm(Form):
     ])
     move_to = NestedRadioField(
         'Choose a folder',
+        default='',
         validators=[
             Optional(),
             required_for_ops('move-to-new-folder', 'move-to-existing-folder')

app/main/views/templates.py

@@ -122,6 +122,7 @@ def choose_template(service_id, template_type='all', template_folder_id=None):
             len(user_api_client.get_service_ids_for_user(current_user)) > 1
         ),
     )
+    option_hints = {template_folder_id: 'current folder'}
 
     if request.method == 'POST' and templates_and_folders_form.validate_on_submit():
         if not can_manage_folders():
@@ -149,7 +150,8 @@ def choose_template(service_id, template_type='all', template_folder_id=None):
         template_type=template_type,
         search_form=SearchTemplatesForm(),
         templates_and_folders_form=templates_and_folders_form,
-        move_to_children=templates_and_folders_form.move_to.children()
+        move_to_children=templates_and_folders_form.move_to.children(),
+        option_hints=option_hints
     )